Solar has arrived 16

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1. 

   Whiskerfish Posted 8:45 pm
   24 Jul 2007

   conc solar vs spread-out stuffWhat does this have to say about conc solar?
   http://environment.guardian.co.uk/conservation/story/0,,2 ...
   Whiskerfish

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2. 

   GreyFlcn Posted 11:53 pm
   24 Jul 2007

   While this is trueIt's Southern California Edison or San Diego Gas and Electric which is doing the dishes.
   
   http://www.stirlingenergy.com/breaking_news.htm
   PG&E is instead opting for heliostats from Luz II.
   http://www.luz2.com/templates/professional/412/main/en/gf ...
   
   http://www.luz2.com/agallery%20presentation/c4123/45365.p ...
   
   http://www.luz2.com/agallery%20presentation/c4119.php

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3. 

   sunflower Posted 11:55 pm
   24 Jul 2007

   Depends on climate and efficiencySunny climates about 900 barrels of oil equivalent per acre per year, half that in cloudy climates.  Concentrators are spaced apart, like fruit trees.
   The PG&E market is a drop in the bucket, and they are not choosing technology, just offering to buy a supply of solar megawatts, unfortunately not solar negawatts.  
   Heliostats can be located over parking lots, over sidewalks, both sides of roads, on top of buildings, on brown fields, ... creating urban shade while supplying community heating, cooling, and electricity.

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4. 

   GreyFlcn Posted 12:00 am
   25 Jul 2007

   Read a little deeper pleaseBiofuels
   
   A generator burning biomass requires crops from 250,000 hectares to match the electricity output of a nuclear power station. (About 0.2% of US electricity needs)
   Solar power
   
   Photovoltaic cells covering an area of 150,000 square kilometres would be needed to meet the entire US electricity need for a year. To power New York city would take 12,000 square kilometres, about the size of Connecticut.
   http://environment.guardian.co.uk/conservation/story/0,,2 ...
   All the report is primarily saying is that biofuels are a dumb idea.
   
   http://greyfalcon.net/ethanol.png
   Wind and Solar are no more massive than existing power plants.

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5. 

   Jon Rynn Posted 1:17 am
   25 Jul 2007

   GreyFlcn, Compare his report......to "The renewable path to energy security", page 20; these authors seem to think that solar/wind could be done without using massive amounts of land; also the author you cite was talking about replacing allenergy with wind or solar, not just electricity, which makes the situation much worse.

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6. 

   sunflower Posted 1:21 am
   25 Jul 2007

   Replacing all energy with solar pv electricity

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7. 

   rmcleod Posted 1:53 am
   25 Jul 2007

   Energy is not WorkPeople who forecast the cost of 'replacing all energy consumption with (renewable) electricity' generally do not understand the concept of entropy.  Joule per joule, electricity can do more work then a unit of oil or coal.  Practically, electricity can do approximately 3x the work of a fossil fuel.  Consider home heating.  A joule of natural gas provides a joule of heat, but a joule of electricity can provide ~3.5 joules of heat with a heat pump.
   
   
   
   --
   
   entropyproduction.blogspot.com

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8. 

   sunflower Posted 2:18 am
   25 Jul 2007

   Not the same energyCollecting ambient heat is like collecting solar heat, it is another energy source.  A solar heat collector will cost less and amplify the heat of parasitic electricity consumption much more than a heat pump.  The laws of entropy still apply when all energy inputs are accounted for.

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9. 

   jimandre Posted 3:49 am
   25 Jul 2007

   Chose solar over wilderness?What the article unfortunately fails to mention is that the planned monster solar developments in "The Mojave Desert" will utilize as their footprint thousands of acres of pristine desert habitat that home to thousands of species of plants and animals, including the desert tortoise.  The Mojave Desert remains one of last great wild areas in the U.S. These would be scenic and wild public lands (BLM) transferred to private industry.  The folly of these plans is that solar development can occur anywhere there is sun, including the rooftops of urban environments as found in L.A. and San Diego.  But in this corporate plan, the "desert wasteland" is instead sacrificed, ensuring higher profits for corporations and a higher cost to the consumer.  But more importantly, the sacrifice of native plant/animal biodiversity is yet another example  of man's way of doing things....a la clearcutting, strip mining, leap-frogging....to maximize profit over wise earth stewardship.  I'm against this kind of solar power.  
   
   James M. Andre

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10. 

    Jon Rynn Posted 4:53 am
    25 Jul 2007

    What would you say......if Death Valley was covered over with solar energy systems, and in return, all coal plants were shut down?  Would that be a good exchange?  In a previous comment, I noted a study that refers to an IEA study that claims that over half of our electricity needs can be met by putting solar on rooftops and facades, although I might also advocate using rooftops for gardens; is it possible to use some parts of some deserts for concentrated solar, which is more efficient than PVs?

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11. 

    sunflower Posted 5:09 am
    25 Jul 2007

    Desert heatThe desert is not the best location for solar concentrators.
    These devices should be distributed near people.  Cooling the power cycle for making power is both expensive and wasteful in a desert.  A better heat sink is cogenerating power with waste heat applied to heating, cooling, and industry.  Solar is very low cost to displace natural gas used for thermal loads.
    Further, even expensive land is a small percentage of solar power plant costs, so no worries there.

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12. 

    Jon Rynn Posted 5:21 am
    25 Jul 2007

    That's fascinating......so you're saying that it wouldn't make sense to take a big chunk of a very sunny area, as in a desert, and generate a huge amount of electricity there?  You could put these concentrated solar installations near cities and towns?  That's fine with me, I would prefer a decentralized energy grid, I was just under the impression that those installations are so big they need to be in the desert.

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13. 

    sunflower Posted 5:58 am
    25 Jul 2007

    Just a mirror on a stick.Concentrator systems can be any size system, from a 1 kW(e) dish to a 10+ MW(e) heliostat field.  Size matters on choice of geometry.
    There is push, pull, and science.  The science wants record breaking efficiencies and performances.  The pull wants electrical power (due to government/industry interference).  The push wants return on investment.  
    It is a virgin market so the push, like a kid in a candy store, can choose the most valued customers.  From cost, risk, and fast payback perspectives, the best customers are low grade heat consumers, especially electric and natural gas hot water and/or wet steam users.  
    The concentrator field is sized to the thermal load to be quickly amortized by the thermal load (rapid scale up wants 3 years).  High-intensity 40% efficient multijunction pv cells are laminated on the cold end of the receivers to cogenerate some power.  The thermal load is the milk, the power is the creme off the top.
    A very low cost field of dish or heliostat concentrators + high power would start at $200,000 per acre.
    
    

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14. 

    Pangolin Posted 5:46 pm
    25 Jul 2007

    They are as small as a satelite dish(old style)http://www.sunmachine.de/english/main.html
    
    http://www.infiniacorp.com/applications/clean_energy.htm
    It would be far more efficient to mount these units next to buildings where the waste heat could heat water, run AC's, or provide space heating.
    My idea is that you oversize the solar collector and feed excess heat into a geothermal well. Then at night or on cloudy days you tap the well and run the stirling on the back end of the cycle.
    Storing solar power is as simple as pumping steam down a well. Sure you don't get it all back but when your cool side is colder (at night maybe) the stirling engine still works as if the hot side was still hotter. Solar and geo-exchange is the ideal combination in my book.
    
    Put the Carbon Back

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15. 

    Steve Beckendorf Posted 10:12 am
    03 Aug 2007

    concentrating solar power and the desertI'm concerned by James Andre's rejection of concentrating solar power on the basis of concerns for the desert environment.  In projecting the potential of CSP in California and other southwest US states, the National Renewable Energy Lab (NREL) and others have tried to exclude environmentally sensitive land from consideration.  After excluding parks, wilderness areas, and similar lands along with any land that slopes at more than 1% and any land that is remote from transmission lines, they conclude that if fully developed, CSP in the SW US could supply over seven times the total US electricity usage requirements.  The potential is vast, but of course no one is suggesting that all of this potential be developed at anytime soon.
    The second thing to say about environmental effects of CSP is that planning processes underway in California now (initiated by the CA PUC) are consulting with environmental groups that are active in the Mojave.  At a recent workshop in southern CA, the largest concerns were about the water requirements needed for cooling.  Obviously, deserts are not places with a lot of water and it would be a big mistake if CSP plants pulled the scarce water away from the habitat.  How that will be resolved is unclear, but there is a possibility to use air cooled plants, though their efficiency would be reduced.
    I also want to clarify a couple of things about the technology.  First, the PG&E power purchase agreement was for a huge parabolic trough power plant, not for dishes or heliostats.  Second, CSP only works in areas with high incident solar irradiation that is available nearly every day of the year.  This limits its application to a few arid parts of the world - the US southwest, Spain, North Africa, some places in the middle east, parts of South America, western Australia.  A final misconception I've seen in several reports about CSP is that it only provides power when the sun shines.  In fact, liquids heated by the sun can be stored for many hours (6-16 depending on the technology) and then used in the evening or during the night to generate steam to spin turbines.
    
    Steve Beckendorf
    
    UC Berkeley

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16. 

    GreyFlcn Posted 11:34 am
    03 Aug 2007

    WaterObviously, deserts are not places with a lot of water and it would be a big mistake if CSP plants pulled the scarce water away from the habitat.
    Well thats one of the obvious advantages of Stirling Dishes.
    No water requirements.

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